Intelligence and Communication
Fact or Fiction?:
Nothing about dolphins has been more widely or passionately discussed than their supposed intelligence and communication abilities. A persistent dogma holds that dolphins are among the most intelligent of animals and that they communicate with one another in complex ways. Implicit in this argument is the belief that dolphins cultures are at least as ancient and rich as our own.
To support the claim of high intelligence amongst dolphins, proponents note that they have large brains, live in societies marked as much by co-operative as by competitive interactions and learn the artificial tasks given to them in captivity. Dolphins do indeed learn through observation and have good memories. Captive dolphins demonstrate, playfulness, are quick to comprehend body language and commands, show mental agility and emotional resilience and demonstrate a sense of humor.
It is misleading to speak of 'the dolphin brain'. Among the many different species of toothed cetaceans, there is great variation in brain size and brain anatomy. Adult franciscanas and Ganges river dolphins have relatively simple-looking brains weighing only about 200g (7oz), while those of several delphinid species are highly convoluted and weigh well over 1.5kg (3lbs 5oz). Absolute brain size is not necessarily a measure of intelligence, since there is a trend for brain size to increase with body size. Scientists have adopted the concept of an 'encephalization quotient' (EQ) which takes this trend into account.
The EQ, simply stated, is the ratio of brain mass to body mass. Most cetaceans have EQ's similar to those of gorillas, orangutans and chimpanzees. In addition to their large size, dolphins' brains have extremely convoluted cerebral hemispheres.
The EQ rating and the convolutions of the brain however still do not provide us with a direct measure of intelligence. In fact the latest studies of dolphins' brains show that they seem to be stuck at an early evolutionary stage of development, - the most primitive stage in land mammals - with a cortex that appears to lack even some features that are characteristic of hedgehogs.
The extremely varied repertoires of sounds made by dolphins are often invoked as prima facie evidence of advanced communication abilities. These sounds actually consist of a very limited number of vocalizations, namely whistles and clicks. The latter are used solely for echolocation, the former for identification and indications of mood. Dolphins do gather information about their environment and broadcast it but there is no 'intent', in human terms, involved. They use whistles and body language to identify themselves individually but there is no evidence of enough variety in the sounds to constitute anything approaching a language.
It would be wrong to argue that dolphins are not communicative creatures. Not only is there abundant evidence that they exchange information acoustically but it is equally obvious that they communicate by body contact - through rubbing, stroking and biting.
The issues of dolphin intelligence and communication have been inseparable in most people's minds, and the presumed existence of one has been taken as proof of the other, a classic tautology. Not surprisingly then, most experiments to evaluate dolphin intelligence have measured the animals' capacity for cognitive processing, as exhibited in their understanding of the rudiments of language.
Experiments to establish if dolphins can accept simple information, in the form of acoustic or visual symbols representing verbs and nouns, and then to act on the information following a set of commands, have revealed disappointing results. Either we have not yet devised adequate tests to permit us to detect, measure and rank intelligence as a measure of a given species' ability to communicate, or we must acknowledge that the characteristics which we regard as rudimentary evidence of intelligence are held more commonly by many 'lower' animals than we previously thought.
The fact remains, however, that when one encounters dolphins one is struck by their sense of 'awareness'. The scientific evidence may be inconclusive and disappointing but we humans seem willing to let the question of their intelligence and communication rest.
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